Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753408AbbBXKZw (ORCPT ); Tue, 24 Feb 2015 05:25:52 -0500 Received: from mail-we0-f171.google.com ([74.125.82.171]:33216 "EHLO mail-we0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751179AbbBXKZu (ORCPT ); Tue, 24 Feb 2015 05:25:50 -0500 Date: Tue, 24 Feb 2015 11:25:45 +0100 From: Ingo Molnar To: Pavel Machek Cc: Jiri Kosina , Vojtech Pavlik , Josh Poimboeuf , Peter Zijlstra , Andrew Morton , Ingo Molnar , Seth Jennings , linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven , Thomas Gleixner , Peter Zijlstra , Borislav Petkov Subject: Re: live kernel upgrades (was: live kernel patching design) Message-ID: <20150224102545.GD19976@gmail.com> References: <20150220214613.GA21598@suse.com> <20150221181852.GA8406@gmail.com> <20150221191607.GA9534@gmail.com> <20150221194840.GA10126@gmail.com> <20150222084601.GA23491@gmail.com> <20150222094639.GA23684@gmail.com> <20150223113908.GA3206@Nokia-N900> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150223113908.GA3206@Nokia-N900> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1448 Lines: 44 * Pavel Machek wrote: > > More importantly, both kGraft and kpatch are pretty limited > > in what kinds of updates they allow, and neither kGraft nor > > kpatch has any clear path towards applying more complex > > fixes to kernel images that I can see: kGraft can only > > apply the simplest of fixes where both versions of a > > function are interchangeable, and kpatch is only marginally > > better at that - and that's pretty fundamental to both > > projects! > > > > I think all of these problems could be resolved by shooting > > for the moon instead: > > > > - work towards allowing arbitrary live kernel upgrades! > > > > not just 'live kernel patches'. > > Note that live kernel upgrade would have interesting > implications outside kernel: > > 1) glibc does "what kernel version is this?" caches > result and alters behaviour accordingly. That should be OK, as a new kernel will be ABI compatible with an old kernel. A later optimization could update the glibc cache on an upgrade, fortunately both projects are open source. > 2) apps will do recently_introduced_syscall(), get error > and not attempt it again. That should be fine too. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/